Enhancement of technology from old preservatives to new preservatives and latest development in the field of preservation

Wood preservatives are usually protecting the wood products from deterioration. Various methods of treatment can be practiced to incorporate the preservatives inside the wood depending upon the application of end product. Ultimately the preservative enhance the dimensional properties and provide resistance to wood products from biological pathogens. Improvement in the present situation of wood preservation in tropical countries would result in a great reduction of wood losses. Losses resulting from lack of preservation are strikingly high compared with the costs of preservation. Chemical and thermal modification are the most popular method of treatment from 20th century. The greatest impact on wood preservation in the 20th century is the invention of Chromated copper arsenate (CCA) preservatives which is gaining a lot of attention afterwards. The preservative used earlier are oily liquid preservatives like creosite, creosote oil and coal tar, petroleum but application of modern technology in the latest developed preservatives have grate efficiency over the earlier.

Review Article https://doi.org/10.20546/ijcmas.2019.801.227

Enhancement of Technology from Old Preservatives to New Preservatives

and Latest Development in the Field of Preservation

Sonia Panigrahi 1 * and Sadhna Tripathy 2

1

M.S.Swaminathan School of Agriculture, CUTM, Paralakhemundi-761200(Odisha), India

2

Forest Product Division, Forest Research Institute, Dehradun- 248195, India

*Corresponding author

A B S T R A C T

Introduction

Wood preservation was first introduced as an

industrial process in England and it has

continued to be used in situation where decay

is otherwise inevitable such as for railway

sleepers and transmission pole It must be

accepted that wood decay is inevitable for

example- fungal decay is dependent on

moisture content, so that a structure designed

to maintain wood in a dry condition is

sufficient to ensure freedom from fungal

decay, whatever the species of wood The

preservative treatment required in wood to

increase the lifespan of the material and reduce the replacement of the material But preservation involves additional cost and must clearly be justified The environmentalist may see preservation as a mean for reducing our demand for replacement wood, thus conserving our forest Wood importing countries will wish to reduce wood import as

to reduce currency while the wood exporting countries will adopt preservation in order to reduce home demand for replacement wood, thus leaving the maximum volume available for export Wood preservation is the pressure

or thermal impregnation of chemicals into

International Journal of Current Microbiology and Applied Sciences

ISSN: 2319-7706 Volume 8 Number 01 (2019)

Journal homepage: http://www.ijcmas.com

Wood preservatives are usually protecting the wood products from deterioration Various methods of treatment can be practiced to incorporate the preservatives inside the wood depending upon the application of end product Ultimately the preservative enhance the dimensional properties and provide resistance to wood products from biological pathogens Improvement in the present situation of wood preservation in tropical countries would result in a great reduction of wood losses Losses resulting from lack of preservation are strikingly high compared with the costs of preservation Chemical and thermal modification are the most popular method of treatment from 20th century The greatest impact on wood preservation in the 20th century is the invention of Chromated copper arsenate (CCA) preservatives which is gaining a lot of attention afterwards The preservative used earlier are oily liquid preservatives like creosite, creosote oil and coal tar, petroleum but application of modern technology in the latest developed preservatives have grate efficiency over the earlier

K e y w o r d s

Chromated Copper

Arsenate (CCA),

Acza, Electro

pulsing technology,

Creosote oil

Accepted:

14 December 2018

Available Online:

10 January 2019

Article Info

wood to a depth that will provide effective

long-term resistance to attack by fungi, insects

and marine borers By extending the service

life of timber, wood preservation reduces the

harvest of valuable forestry resources, reduces

operating costs in industries such as utility and

railroads, and ensures safe conditions where

timbers are used as support structures In

addition to industrial and commercial

application, a significant part of the treated

wood volume is used for residential

construction to protect homeowners'

investments and provide outdoor living spaces

that are a desired part of the Canadian way of

living As indicated earlier, these costs show

that the average cost of wood preservation in

tropical countries may amount to about 20 to

30 percent of the cost of the timber used and

that the service life of treated wood may be 5

or more times as long (Swiderski, 1997) The

use of preservative chemicals and treated

wood has been and still is sometimes

criticized on the basis of health or

environmental concerns Ignorance on the part

of the treating industry, poor work practices

and lax environmental regulation all share part

of the blame for that negative perception

Innovation in the first half of the 20th century

led to the development of more effective wood

protecting chemicals and processing

techniques that turned a specialty industry into

a commodity business (Preston, 2000) As can

happen in all commodity businesses, research

and development was not sustained when

profit margins began to fall and the door was

opened for competitive products such as

plastics, concrete and steel (Kevin Archer and

Stan Lebow, 2006)

About wood preservatives

Some species are naturally durable as the

Sapwood is rarely durable, the heartwood of

many tree species exhibits some degree of

resistance to attack by decay fungi and insects,

This natural durability can be attributed to a

combination of toxic extractives present in the wood and low inherent permeability As a result of this natural durability such woods can

be used outdoors and in some cases in ground contact or submersed in water Wood from naturally durable species is sometimes viewed

as being environmentally preferable to chemically treated wood, and many of these species have an attractive appearance In addition, some species such as black locust, greenheart and ipe also have excellent strength

properties (Green et al., 1999) As might be

expected such a combination of desirable attributes has led to increasing interest in use

of durable species from the tropical countries for construction in North America and Europe However, several factors limit the use of naturally durable species In developed countries the volume of growing stock of

relatively low compared to the demand for dur able wood products.(www fpl.fs.fed.us/docu mnts/pdf2006/fpl_2006_archer001.pdf) In view of the limited supply of natural durable wood species, it is valuable to supply of less durable wood treated with preservatives Preservatives treatment of timber therefore it

is important to conserve the wood sources of

the country

Wood preservatives are chemical substances that when suitably applied to wood, make it resistance to fungi, insect and woodborer There are two general classes of wood preservatives: oils, such as creosote and petroleum solutions of pentachlorophenol; and waterborne salts that are applied as water solutions The effectiveness of the preservatives varies greatly and can depend not only upon its composition, but also upon the quantity injected into the wood, the depth

of penetration, and the conditions to which the treated material is exposed in service (Wood Preserving Industry Production Statistical Report, 1996)

The choice of wood preservatives depends

upon the character of the wood to be treated,

the anticipated service and the properties of

the chemical or formulation Wood

preservation formulations must:

protect against attacking organisms;

be able to penetrate wood;

remain in the wood for the length of the

intended service;

be chemically stable;

be safe to handle;

be economical to use; preservatives are two

types either oily liquids or metallic

compounds

Major used wood preservatives are:-

Pentachlorophenol

Creosote

Inorganic salts

Amonical cupper arsenate

Chromate cupper arsenate- Acid cupper

chromate

Chromate zinc chloride

Minor used wood preservatives

Copper naphthenate

Copper 8

Tributyltin oxide

New preservatives

Alkylammonium compounds(AAC)

Di –alkyl dimethyl ammonium

Advantages of wood preservatives are

clean, colourless, odourless and paintable

They should not cause more than

minimal swelling

A wood preservatives must be toxic to

the insect, pest, fungi, borer It must be able

to be absorbed and held by the wood so that it

does not leach out into the environment The

ingredients of most preservatives are potent, capable of causing poisoning as small as a few drops or few grams

Preservatives used earlier

In Europe the first attempt were taken by placing of stone blocks under wooden pillars

to keep away soil and vegetation

Later on olive oil or other essential oil were used as they kept the wood free from insect attack

M Paulet in his book entitled “conservation des Bios” enumerates 173 processes or methods that were tried, most of which proved unsuccessful It was during the 1st quadrate of the 19th century that modern methods of injecting wood may be considered as beginning although the most successful attempts did not come until a few years later Mercuric chloride was used by Homberg in

1705 and by De Boissiew in 1967.The use is commonly called kyanizing

Copper sulphate recommended by De Boissiew and Bordenava in 1967 and best known as margaryzing

Chloride of zinc recommended in 1815 by Thomas Wade and by Boucherie in 1837 and referred as burnettizing (Samuel B Boulton, 1885)

The treatment of green timber with creosote

by first using steam followed by a vacuum prior to impregnation with the oil is attributed

to Hayfor (Jornal of Franklin institute, 1878) Oily liquids preservatives used earlier

Creosote oil, carboleneum, shale oil used as wood preservatives in 1848 suggested by Hutin and Boutigny in 1848

The chemicals recommended in the year and used in various countries

Creosote oil + coal tar + petroleum

1920

Metallic compounds

Mercury chloride 1705

Zinc sulphate World war 2

Inorganic compounds

Boron compound – used as fire retardants in

wood (1933)

Chromium compound – used as admixtures in

water soluble preservatives salts (1938)

Organic compounds

Chlorinated phenols, Chlorinated cresols and

xylonols, Chlorinated napthalenes (1913),

Nitrated phenols and cresols-19th centuries,

Chlorinated benzenes (1940 onwards),

dichloro diphenyl-trichloroethane (DDT),

Organic mercury compounds (Brosevan

Groenou et al., 1952)

Preservatives used presently

Oil and oil borne preservatives used are the

Coal tar, creosote solution, petroleum fuel oil

The principal toxic chemical used is

pentachlorophenol It has very low solubility

in water and low volatility and is very stable

chemical therefore it is most promising and

widely used preservatives of oil borne

chemical type Demerits - It has been found ineffective against marine borers and never used for the protection of wood in salt water Waterborne preservatives used are arsenic salt, borax and boric acid, chromium salt, cupper sulphate, mercuric chloride, nickel salt, sodium chloride, zinc chloride

Demerits - These are highly toxic to the human body and animal (Ref:-Gorge M Hunt and George A Garratt 1953)

In European country wood preservatives are used –

In England creosoting is most popular method, in Germany creosote and zinc chloride are extensively used In France the timbers and poles are impregnated with copper sulphate, in United states modern preservation begins in the country in 1875 creosoting is the popular method (Howard F Wiess)

In United States zinc chloride, creosote, coaltar, carbonelium salt The production of low temperature coal tar, creosote in 1950 was negligible in the USA but in England it

was used The incising of poles is confined to

northern white cedar and western red cedar

and also for Douglas fir, wastern larch

(American Wood Preservers Association,

1916 handbook on wood preservation)

Living tree can be treated by preservatives

like Banding method, Capping method,

Stepping method, Pitch treatment of standing

trees

Non pressure process used for preservation

are Dipping method, Steeping method,

Kyanizing, other methods used are cold

soaking, hot and cold bath, diffusion

processes (George M Hunt and George A

Garratt, 1953) Copper compounds are used

as preservatives Cation exchange capacity

test on some lignocellulosic material highlight

some aspect of the use copper as wood

preservatives (Sttaccioli et al., 2000)

The greatest impact on wood preservation in

the 20th century is the invention of chromated

copper arsenate (CCA) preservatives by Sonti

Kamesam in India in the 1930‟s It involved

development of a product that balanced needs

for availability of active biocides against

invading organisms with stability against

leaching It served the industry extremely

well, long before mechanisms of fixation and

other environment and health related issues

were well understood or appreciated

In Canada the predominant wood preservative

chemicals or formulations are as follows

-Aqueous based formulations for residential

use:

ACQ (alkaline copper quaternary) -

ACQ-treated products include lumber for patios and

fencing in residential construction

CA-B (copper azole) - CA-B-treated products

include lumber for patios and fencing in

residential construction

Borates - Uses are for wood components in

interior applications

Aqueous based formulations for commercial and industrial use:

CCA (chromated copper arsenate) - CCA-treated products include agricultural fence posts, foundation lumber and plywood, utility poles and construction timber Chromated copper arsenate (CCA) is used in pressure-treated wood to protect it from dry rot, fungi, molds, termites, and other pests This wood is used in decks, wooden playground equipment, picnic tables, gazebos, bridges, and other outdoor wood products In May 2001, the Environmental Working Group petitioned the Consumer Product Safety Commission to ban the use of CCA-treated wood in playground equipment (Dr Champaign Illinois Sustainable Technology Center) ACZA (ammonical copper zinc arsenate) – ACZA treated products include marine structures and construction timbers At the time of publication, this preservative was not

in use in Canada

Oil based formulations for commercial and industrial use:

PCP (pentachlorophenol) - PCP-treated products include utility poles and cross-arms Creosote - Uses include treatment of railway ties, utility poles for export, and pilings and timbers for marine applications

The development of alternative chemicals for wood preservation is the subject of ongoing research The use of alternative chemicals will depend on industry and safety evaluations, and on approval under the Pest Control Products Act (PCPA), administrated by Health Canada's Pest Management Regulatory Agency (PMRA)

In India the preservatives used mostly are creosote, pentachlorophenol, CCA, CCB, ACC, boric acids and borax A number of

compositions like ASCU, ASCU boric

(CCB), pentachlorophenol aldrin, creosote are

available in India Fire retardant treatment of

plywood, fibre board is also carried out by the

chemical composition which is recommended

in Indian standards (Arnon, 1965 and 1980;

Satish Kumar and Indra Dev, 1993)

Technology involved in wood preservation

Drying - Drying increases preservative

penetration and also ensures, for larger

timbers and roundstock, that much of the

checking occurs before treatment If timber is

not adequately dried there is the risk that

these checks might subsequently extend into

untreated wood when the timber is in service

Incising - Douglas fir, larch and spruce, are

very resistant to the penetration of

preservatives and can only be pressure treated

effectively if incised When treating poles,

incisions can be concentrated on the region

close to the groundline, so putting the

preservative where it is most needed

Steaming or Boultonizing processes - In the

steaming process green wood is steamed in a

pressurised treating cylinder for several hours

usually at a maximum temperature of 118°C

(245°F) so that the outer annulus of wood is

heated above 100°C

Vacuum/pressure impregnation treatments -

These techniques result in deep penetration of

permeable timbers while at the same time

controlling the amount of preservative

Retained

Modified full cell or 'low weight' method

Vacuum treatments - In this process

atmospheric pressure may be thought of as the

pressure period Vacuum treatments have

been commonly used for treatment of dry

profiled or machined components (millwork)

using preservatives carried in light organic solvents Sonic waves are used in pressure treatment of Douglas fir and ponderosa pine and the result indicate that sonic waves more significant potential for the improvement of pressure treating process and the treatment of refractory wood (Nair and Simonsen, 1995)

Wood modification

The durability of wood can be improved through wood modification, this can be

achieved through:

Heat treatment Accetylation (accoya) Furfurylation

Silicone/silane Oil /wax /paraffin Melamine resin

Thermowood: chemicals are not used, Temperature 180ᵒC to 220ᵒC Producers are Finland, Netherland, Russia, France, Germany

Acetylation: Impregnation with acitic anhydride, reaction at elevated temperature, post treatment with acitic acid acetylated wood is dimensionally stable and resistant to rot Its durability remains unchanged and the timber split less than untreated wood ex: accoya wood

Furfurylation: Is the pressure treatment of wood with a solution of furfuryl alcohol made from bio mass waste after drying and hardening the reselt is hard heavy and dimensionaly stable timber are obtain that is resistant to rot

Silicon impregnation: The method uses no biocides or fungus inhibiting preparation insted imitating the natural fossilisation process that occurs in inorganic material such

as wood as they turn into fossils

-the-right-wood-preservation.)

Plasma treatment

It is a versatile and powerful technique: by

producing high frequency electric discharges,

plasma generates 'ionised' gas that can change

the surface properties of the material it is in

contact with Bugnicourt says the consortium

looked at plasma treatments as they can either

„hydrophobic‟ (waterproof) wood surfaces or

makes them more compatible with waterborne

coatings the plasma pre-treatment a

cost-efficient, durable, and environmentally

friendly technology, could add five to seven

years life to the wood

Pleot–electro pulsing technology for wood

protection

If PLEOT is installed, the moist wooden

material conducts electric current This

self-regulating typical areas of application for

impregnated wood are terraces, construction

materials, cladding, playgrounds,

noise-deflection walls, guardrails, telephone poles

In addition, the technology can be applied to

protect wooden windows and doors System

consumes a minimal amount of power and

can for instance be run by a solar panel

It is likely to conclude that the PLEOT system

was influencing not only the directly

connected samples but also the untreated

samples since the untreated samples were in

the same soil and container as the treated

ones The PLEOT system could thereby lower

the mass loss of the untreated samples New

test setup is necessary to verify these results

Average mass loss of CCA- and PLEOT-

treated and untreated Scots pine samples

(Pinus sylvestris) after 32 weeks in soil

contact; the samples showed a wood moisture

content after the test of 124 (11) % PLEOT,

100 (21) % and 165 (14) untreated (Treu and Larnøy, 2010)

Environmental causes of preservatives

Various wood preservatives developed by TsNIIMOD organisation in Russia and which

do not contain chlorophenols The preservatives are k-1 (main toxic ingredients organic compounds of aliphatic series), EOK, K-12(F SALTS) and Katan (Varfolomeev, Yua, 1995)

In 1978, the united state environmental protection agency (USEPA) uses three preservatives for the treatment of lumber creosote, inorganic arsenical and pentachlorophenol (penta) But after some years pentachlorophenol and arsenical are restricted as they are harmful to humans, these are declared as restricted use pesticides

(Patrick J Marer and Mark Grimes, 1992)

Cca treated wood should never be burned, as the smoke particle inhaled and can be toxic.3 (Dobbs and Grant, 1978)

Nymphs of Potamanthus luteus were found in

Kymijoki River, Southern Finland in 1997 The nymphs collected from the badly contaminated site had generally darkened gills, possibly indicating impacts of pollution (Vuori, 1999) In 2003 the Environmental Risk Management Authority of New Zealand conducted an extensive independent review of CCA-related cancer risk estimate studies which included five major studies conducted subsequent to the updated As human cancer potency factor developed by the National Academy of Science‟s Natural Research Council in 2001 (Helena Solo-Gabriele, 2004)

The presence of some types of inorganic ions

in water has been reported to increase leaching from CCA treated wood, Water pH

can also affect leaching of preservatives

Leaching of CCA is greatly increased when

the pH of the leaching water is lowered to

below 3, and the wood itself also begins to

degrade Most controlled leaching trials of

preservative treated wood samples to leaching

via immersion Immersion is perhaps the

simplest type of leaching mechanism to

control and replicate, and it provides a severe

leaching environment (Stan Lebow et al.,

2004)

Wood preservatives can be harmful to

humans if not properly handled The exposure

routes by which they can enter the human

body are inhalation (vapour, dust, aerosol,

etc.), ingestion (solid, liquid), ocular exposure

and through the skin (vapour, liquid, solid) A

number of studies have examined the effects

of wood preservatives on settlement patterns,

growth and biomass development of human

of environments The majority of leaching

from wood when treated with waterborne

preservatives, The rate and overall amount of

leaching from a given product is also affected

by preservative penetration and retention and

by the surface area of the product

Strategies

The current international trends are to:

1) Use less preservative, through use of

alternative materials such as concrete ties,

other materials for poles, use of untreated

wood and movement to wood modification

(chemical and thermal) to protect wood

2) Decrease the accepted limits of pesticides

in drinking water, surface water, soil,

sediments, food etc This makes it more

difficult to comply with regulations and

guidelines at all stages of the life cycle for

certain preservatives

3) Reduce use of arsenic, chromium, creosote

and pentachlorophenol containing preservatives and probably in the longer term, copper containing preservatives In parallel with this, the trend is for introduction of a much broader suite of alternatives, with main focus on organic preservatives

4) Increase reliance on incineration for disposal of most spent wood including treated wood

For example, in 1991, Japan incinerated 40%

of its waste wood (Honda et al., 1991)

Holland and Germany (by 2005) will both ban landfilling of waste containing more than a specified amount of organic material (Peek 1999)

5) Recover inorganic preservatives from treated wood by collecting and treating ashes and condensate from co-generation or incineration facilities (Italy and Finland) 6) Require manufacturers to take full life responsibility for their products

In conclusion, the great variety of wood-destroying insects and fungi in tropical countries constitutes a much greater danger for timber used in such areas elsewhere in the world High temperature and high atmospheric humidity, together with the extraordinarily large number of nondurable wood species, render timber in the tropics particularly vulnerable to decomposition Consumption of sawnwood and wood used in the round is expected to rise considerably in the tropics during the period from 1961 to

1975 The expected growth rate (70 percent)

is likely to be more than three times higher there than in the rest of the world The value

of timber used in tropical countries as sawnwood and roundwood amounted to approximately $2100 million in 1966

(Swiderski) A considerable proportion of this

value could be saved annually through expanding the preservation treatment of

wood The average cost of preservation may

amount to 25 to 35 percent of the initial value

of the wood and ensures a service life of not

less than three to five times that of untreated

timber The average investment costs for

establishing a pressure-treatment plant are

low ($5 per cubic metre per year); this makes

it possible to establish the necessary

capacities with a comparatively small capital

expenditure and over a short period of time

Wood preservation makes it possible to

reserve precious durable species for export

markets by replacing them on local markets

with less durable but properly treated timbers

It is also a necessary condition for export

trade in many wood products which are

vulnerable to damage by fungi or insects In

many countries where naturally durable

species are nearing depletion, utilization of

properly treated secondary species constitutes

the only way in which the utilization of wood

in most of its applications can be maintained

References

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IInd edition

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volatisation of arsenic on burning

cupper chromate arsenic treated wood

holzforchung 32(1)

Gorge M Hunt and George A Garratt 1953

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Helena Solo-Gabriele February 8–11, 2004

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How to cite this article:

Sonia Panigrahi and Sadhna Tripathy 2019 Enhancement of Technology from Old Preservatives to New Preservatives and Latest Development in the Field of Preservation

Int.J.Curr.Microbiol.App.Sci 8(01): 2173-2182 doi: https://doi.org/10.20546/ijcmas.2019.801.227